How to integrate mpu-9250 to Android HAL???

Hi,
I am working on a project which use MPU-9250 ,
I understand that the HAL implementation is not the standart
sensor implementation, and its hacked upwards into the SensorManager
using invensenseHAL.so object,
I still dont understand how to achive the fused data transfer into the Filesystem , i can read the RAW values that means that the imu is functioning ,
Is there any refference on the SensorManager using the api???
Or maybe a manual on how to integrate the API???
Thanks